package cn.ac.cintcm.dataconverge.util;

import cn.ac.cintcm.dataconverge.util.PasswordEncoder;

public abstract class BasePasswordEncoder implements PasswordEncoder {
    /**
     * Used by subclasses to extract the password and salt from a merged
     * <code>String</code> created using {@link
     * #mergePasswordAndSalt(String,Object,boolean)}.
     * 
     * <P>
     * The first element in the returned array is the password. The second
     * element is the salt. The salt array element will always be present,
     * even if no salt was found in the <code>mergedPasswordSalt</code>
     * argument.
     * </p>
     *
     * @param mergedPasswordSalt as generated by
     *        <code>mergePasswordAndSalt</code>
     *
     * @return an array, in which the first element is the password and the
     *         second the salt
     *
     * @throws IllegalArgumentException DOCUMENT ME!
     */
    protected String[] demergePasswordAndSalt(String mergedPasswordSalt) {
        if ((mergedPasswordSalt == null) || "".equals(mergedPasswordSalt)) {
            throw new IllegalArgumentException(
                "Cannot pass a null or empty String");
        }

        String password = mergedPasswordSalt;
        String salt = "";

        int saltBegins = mergedPasswordSalt.lastIndexOf("{");

        if ((saltBegins != -1)
            && ((saltBegins + 1) < mergedPasswordSalt.length())) {
            salt = mergedPasswordSalt.substring(saltBegins + 1,
                    mergedPasswordSalt.length() - 1);
            password = mergedPasswordSalt.substring(0, saltBegins);
        }

        return new String[] {password, salt};
    }

    /**
     * Used by subclasses to generate a merged password and salt
     * <code>String</code>.
     * 
     * <P>
     * The generated password will be in the form of
     * <code>password{salt}</code>.
     * </p>
     * 
     * <P>
     * A <code>null</code> can be passed to either method, and will be handled
     * correctly. If the <code>salt</code> is <code>null</code> or empty, the
     * resulting generated password will simply be the passed
     * <code>password</code>. The <code>toString</code> method of the
     * <code>salt</code> will be used to represent the salt.
     * </p>
     *
     * @param password the password to be used (can be <code>null</code>)
     * @param salt the salt to be used (can be <code>null</code>)
     * @param strict ensures salt doesn't contain the delimiters
     *
     * @return a merged password and salt <code>String</code>
     *
     * @throws IllegalArgumentException DOCUMENT ME!
     */
    protected String mergePasswordAndSalt(String password, Object salt,
        boolean strict) {
        if (password == null) {
            password = "";
        }

        if (strict && (salt != null)) {
            if ((salt.toString().lastIndexOf("{") != -1)
                || (salt.toString().lastIndexOf("}") != -1)) {
                throw new IllegalArgumentException(
                    "Cannot use { or } in salt.toString()");
            }
        }

        if ((salt == null) || "".equals(salt)) {
            return password;
        } else {
            return password + "{" + salt.toString() + "}";
        }
    }

}
